1. Field of the Invention
Embodiments disclosed herein generally relate to methods and apparatus for controlling flying height of a slider and a head.
2. Description of the Related Art
Hard disk drives (HDD) include read and write transducers that reside within a slider, which flies over a recording media/disk. Increasing demand in data density requires that the read and write transducers fly closer to the media. As flying heights diminish, it becomes more relevant to accurately control the head-disk distance (i.e., the distance between the read-write heads and the disk). Accordingly, the fly-height between the slider and disk is increasingly important as storage densities also increase.
Heat assisted magnetic recording (HAMR) generally refers to the concept of locally heating a recording media to reduce the coercivity of the media so that an applied magnetic writing field can more easily direct the magnetization of the media during the temporary magnetic softening of the media caused by the heat source. This technique is broadly referred to as “thermally assisted (magnetic) recording” (TAR or TAMR), “energy assisted magnetic recording” (EAMR), or “heat-assisted magnetic recording” (HAMR) which are used interchangeably herein. A tightly confined, high power laser light spot is used to heat a portion of the recording media to substantially reduce the coercivity of the heated portion. Then the heated portion is subjected to a magnetic field that sets the direction of magnetization of the heated portion. In this manner, the coercivity of the media at ambient temperature can be much higher than the coercivity during recording, thereby enabling stability of the recorded bits at much higher storage densities and with much smaller bit cells.
High levels of optical radiation are needed in the HAMR recording head in order to provide rapid heating of magnetic media. A radiation source, such as a laser diode, that produces such levels of optical radiation in combination with a light delivery system is desired. As the radiation source delivers radiation to the recording media for localized heating, the radiation source itself and connected areas of the slider body also heat up. This heating causes a distortion of the slider shape, which leads to flying height changes.
A thermal flying-height control (TFC) device (e.g., a heater element) can be disposed within a slider to contort the slider near the read and write transducers (or elements), which lowers the fly-height for the read and write transducers. With a slider flying as close as possible to a disk, the change in flight dynamics from the heating of the radiation source may cause write element slider-media contact (WEC) to occur. WEC can then create unstable slider-flight dynamics, which in turn, creates data imprint errors in the media.
Thus, there is a need for better control of flying height in magnetic recording devices.